Inlet vane structure for turbines

ABSTRACT

An improved inlet vane structure for axial flow turbines, comprising a plurality of ceramic vanes extending radially outward from an inner shroud ring and supported at their outer end by a blade ring. The vanes are held in a compressed state by spring mounted within the outer ends of a vane support structure. Tapered vane end caps, which are also constructed of ceramic materials, mate with the vanes and provide additional compressive forces on the vanes when the vanes are loaded due to fluid flow.

United States Patent 1191 I t 1111 3,857,649-

Schaller et a1. [4 Dec. 31, 1974 1 INLET VANE STRUCTURE FOR TURBINESFOREIGN PATENTS OR APPLICATIONS 1 1 InvenwrSI Richard Swan", Ambler, Pad826,673 11/1951 Germany 415/214 Stephen D. Leshnoff, Highland Park,57,426 4/ 1902 France NJ. 1,136,350 9/1962 Germany 415/160 [73]Assignee: .Westinghouse Electric Corporation,

1 Pittsburgh p Primary Examiner-C. J. 1-1usar Assistant ExaminerLou1s J.Casaregola [22] Fled: U73 Attorney, Agent, or Firm-D. N. Halgren [21]Appl. No.: 387,069

[57] ABSTRACT [52] US. Cl 415/200, 415/137, 415/214, An improved inletvane structure for axial flow tur- 415/217 bines, comprising a pluralityof ceramic vanes extend- [51] Fold 9/00, Fold 9/02, Fold 25/26 ingradially outward from an inner shroud ring and [58] Field of Search415/191, 214, 200, 212, Supportedat their outer end by a blade ring The115/177, 140,191,1601416/22l241 vanes are held in a compressed state byspring mounted within the outer ends of a vane support 1 Remfllces Citedstructure. Tapered vane end caps, which are also con- UNITED STATESPATENTS structed of ceramic materials, mate with the vanes and 2,801,0767/1957 Terrell et a1. 4151200 Provide additional Compressive forces onthe vanes 3,025,037 3/1962 Beckstrom 415/177 wh n h vanes r lo ded due ofluid flow 3,619,077 11/1971 Wile et a1. 415/214 0 3,719,427 3/1973Davis 415/160 3 Clam, 4 Drawmg Flgures l 1 2 1 36 :I I '1 i I 34 1 1PATENTEDBEU 1- I974 SHEET 1 BF 2 FIG! ILL

FIGZ

N lll 3 2 4 x I 5 24 l Ill]: I I'll E \l 8 [I] E l 5 I H 6 I I ll. 8 S J3 mum 1 INLET VANE STRUCTURE FOR TURBINES The invention herein describedwas made in the course of or under a contract or subcontract thereunderwith The Department of the Army.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to turbines-and more particularly to a support assembly formaintaining first row ceramic inlet guide vanes in a compressed state.

2. Description of the Prior Art The temperatures at which turbinesoperate are constantly being increased to increase the efficiency of theturbine. Raising the operating temperature and hence the efficiency of aturbine also means increasing the temperature of the fluid at the inletnozzle of the turbine. Present inlet nozzles will only function until acertain maximum temperature is reached, then if the efficiency is to befurther improved, the inlet structure must be cooled or materials thatcan withstand higher temperatures must be utilized in the nozzle.Cooling the inlet nozzles require special equipment to create thecooling effect. The power requirements of this special cooling equipmentwill, however, decrease the efficiency gained by the higher inlet fluidtemperatures.

Another method of allowing increasing temperatures at the nozzle inletis to construct the structure from materials that will withstand thehigh temperatures. Ceramics have long been known to withstand hightemperatures, and ceramics are structurally strong when they areutilized in a compressed state. An inlet nozzle structure of ceramicswhich is maintained in compres sion would obviate the need for both acooling effect on the nozzles, and the need for cooling equipment.

German Patent No. 826,673, issued in January, 1952, shows a turbineinlet being guided by radially directed compressive springs. The springsare used to hold the inlet in circular alignment, and are not utilizedto prevent failure of the ceramic inlet nozzle by reducingnoncompressive forces.

SUMMARY OF THE INVENTION In accordance with the present invention, thereis provided an improved inlet vane structure for a gas turbine. Springsare disposed radially outwards of stationary ceramic inlet vanes and endsupports. The springs compress the inlet vanes, through the vane endsupports, and allow for aslight pivotable movement during turbineoperation. An alternative embodiment of the inlet guide vanes iscomprised of ceramic guide vanes that are tapered in the axiallydownstream direction, that mate with supporting ceramic end caps taperedcorrespondingly; wherein a downstream flow of fluid would wedge the vaneinto the end caps creating additional compressive forces within thestructure.

BRIEF DESCRIPTION .OF THE DRAWINGS inward direction taken along the lineIII-III in FIG. 2;

and

FIG. 4 is a perspective view of an alternative embodiment of a vane andend caps.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings indetail, and particularly to FIG. 1, a portion of a gas turbine 10 isshown by a side view of its inlet nozzle arrangement 12. The inletnozzle 12 includes an inner shroud ring 14 which has a plurality ofcircumferentially disposed cooling fluid passageways 16 that allows'acooling fluid to impinge upon an inner supporting structure 17.

The inner supporting structure 17 includes a plurality ofhemispherically-shaped pivot studs 18 circumferentially disposed on theradially outward side of ring 14. The studs 18 each pivotably mate witha convex hemispherically-shaped nobule 20, providing the inlet nozzlearrangement 12 with a slight freedom of movement. A pair of the nobules20 are attached to the radially inward side of each ofa plurality ofcircumferentially disposed inner metal shoes 22. The inner metal shoe 22is in turn, disposed radially inwards of, and supports an insulator pad24. Each metal shoe 22 has a radially outwardly directed lip member 26as shown in FIG. 2, on one of its ends to prevent the insulator pad 24from moving in a circumferential direction. A jambolt 28 extends throughring 14, engages and further restrains the insulator pad 24.

An inner ceramic end cap 34 is disposed on the radially outward side ofinsulator pad 24. The end cap 34 is permitted a slight circumferentialmotion with respect to insulator pad 24 because of a tongue 30 andgroove 32 arrangement therebetween. The track-like components, thetongue 30 in cap 34 and the groove 32 in insulator pad 24 thereby alsoprovide a slight circumferential movability to the entire inletstructure 12.

Each inner end cap 34 has a substantially axially disposed groove 35.Each groove 35 secures the inner end of a radially extending air foilvane 36. Each air foil vane 36 is similarly secured on its radiallyoutward end by a groove 37 in an outer end cap 38.

The support structure radially outward of the air foil vane 36 issimilar to that radially inward of the vane 36, except that acompressive inducing means is disposed outwardly of vane 36.

Each outer end cap 38 has a tongue arrangement 40 which is similar tothat of-inner end cap 34. The tongue 40 slidably interlocks with acircumferentially disposed groove 42 on the radially inward side of eachouter insulator pad 44. The outer tongue 40 and groove 42 arrangementcontributes to the circumferential movement allowable in nozzle inletstructure 12. Each outer insulator pad 44 is disposed in an outer metalshoe 50. The pad 44 is restrained from-circumferential motion byengagement witha jambolt 46 that extends through an outer support ring48 and by a radially inwardly directed lip 51 as shown in FIG. 2 on oneend of shoe 50. The outer shroud ring 48 is coaxial with inner supportring 14, and the two rings 14 and 48 provide the containment for thenozzle.

A cooling fluid passageway 49 is directed through the outer shroud ring48 to allow cooling fluid to impinge upon each outer metal shoe 50.

Each outer shoe 50 has a convex hemisphericallyshaped outer nobule 52attached to its radially outward side. A radially directed plunger 54,has a concave hemispherically-shaped inner end 56 that supports andcooperatively associates with outer nobule 52 to permit shoe 50 to havea movable interface with respect to said plunger 54. The plunger 54 isslidably held in its radial direction by a sleeve member 58 that isintegral with and supported by, outer shroud ring 48.

A bias producing spring member 60 cooperates with plunger 54 to providearadially inwardly directed compressive force upon inlet nozzle members34, 36 and 38, which are constructed from ceramic materials. Thecompressive force upon these ceramic members 34, 36 and 38 prevents theinlet structure from failing under extremely high temperatures.

As is shown in FIG. 2, each outer insulator pad 44 retainstwo vane outerend caps 38 and 38'. Each inner insulator pad 24 likewise retains twoinner end caps, 34

and 34. Each end cap, 34 and 38, supports an end of only one air foilvane 36.

The radially directed lip members, 26 and 51, extending off one endinner shoes 22and outer shoes 50 respectively, are shown in- FIG. 2,each restraining their respective insulator pads, 24 or 44, fromcircumferential motion.

A portion of the outer ring member 48 is shown in the radially inwardlydirected view of FIG. 3.

The ceramic elements of this invention are shown in an alternativeembodiment of FIG. 4. An inner end cap 62 is shown tapered to increasingthickness in the downstream direction. Cap 62 has a circumferentiallydisposed tongue 64 on its radially inward side similar to the tonguearrangement 30 of inner-end cap 34 shown in FIG. 1. End cap 62 has aninclined plane 68 in which a serpentine round bottomed groove 66 isdisposed. A ceramic air foil vane 72 has a correspondingly roundedradially inner end 70 that mates with groove 66 and matches itsconfiguration. The ceramic air foil vane 72 is tapered to decreasingdownstream lengthwise dimensions, and has a radially outer end .74 thatis rounded similar to inner end 70. A ceramic outer end cap 80 isdisposed radially outwardly of the mates with the radially outwardend'74 of vane 72 through a serpentine round bottomed groove 76 disposedon an inclined plane 78 of cap 80 similar to that-of inner end cap 62.

' The outerceramic end cap 80 inclined in the direction of increasingthickness downstream has a tongue 82 arrangement similar to that ofouter end cap 38 shown in FIG. 1.

The inner and outer round bottomed grooves 66 and 76 cooperatively matewith the inner and outer rounded ends 70 and 74 of the radially directedtapered ceramic air foil vane 72. The configuration allows the air foilvane 72 to move relative to the end caps 62 and 80. The ceramiccomponents, the vane 72, and end caps '62 and 80 will have minimumstress concentrations that would be caused by thermal expansion,mismatch, imperfectly joined parts, or notch effects.

Compressive forces, however, generated in this embodiment are compoundedbecause the working fluid moving in the downstream direction imparts aload upon the vane 72 wedging it into end caps 62 and 80,

in addition to the compressive forces caused in the structure by thespring bias producing member 60.

Ceramic materials of the type used in this invention aregencrallysilicon nitride Si N,, or silicon carbide SiC. Their desirability comesfrom the fact that the raw materials are very inexpensive, that they canwithstand very high temperatures and they resist most forms ofdeterioration.

The detailed description of the preferred embodiments of the inventionis not to be considered as limitingor restricting the invention, as manymodifications may be made by those skilled in the art.

We claim:

1. An inlet nozzle for a gas turbine comprising:

a radially inner shroud ring, a radially outer shroud ring coaxial withsaid radially inner shroud ring. a plurality of radially extendingceramic vane structures disposed between said radially inner and saidradially outer shroud rings, each of said vanes being secured at one endto said radially inner shroud ring by an inner support structure, eachof said vanes being secured at its other end to said radially outershroud ring by an outer support structure,

said inner support structure comprising a ceramic end cap, an insulatorpad and an'inner shoe plate disposed on said inner shroud ring,

said outer support structure comprising a ceramic end cap, an insulatorpad, an outer shoe plate and a bias producing means,

said outer shoe plate being movable connected to said bias producingmeans, said bias producing means reacting cooperatively with said outerring, wherein said bias producing means provides a compressive forcedirected radially inwardly on each of said ceramic structures,

said bias producing means consists of a rod-like plunger cooperativelyassociated with a spring member to induce a compressive force upon saidceramic structure, said plunger having a hemispherical surface on itsinner end to provide a movable interface with respect to said outer shoewhich has a mating hemispherical surface.

2. An inlet nozzle for a gas turbine comprising:

a radially inner shroud ring, a radially outer shroud ring coaxial withsaid radially inner shroud ring, a plurality of radially extendingceramic vane structures disposed between said radially inner and saidradially outer shroud rings, each of said vanes being secured at one endto said radially inner shroud ring by an inner support structure, eachof said vanes being secured at its other end to said radially outershroud ring by an outer support structure,

said inner structure comprising a ceramic end cap, an insulator pad andaninsulator plate disposed on said inner shroud ring,

said outer support structure comprising a ceramic end cap, an insulatorpad, an outer shoe plate and a bias producing means,

said outer shoe plate being movably connected to said bias producingmeans, said bias producing means reactingcooperatively with said outerring, wherein said bias producing means provides a compressive forcedirected radially inwardly on each of said ceramic structures,

said end caps having rounded grooves, said end caps having increasingthickness in the downstream direction, said vanes having'their inner andouter ends rounded to mate with said rounded grooves in said end caps,to provide additional compressive forces on said ceramic structures dueto the fluid load upon said vanes in thedirection of elastic fluid flow.

3. An inlet nozzle for a gas turbine comprising:

a radially inner shroud ring, a radially outer shroud ring, apluralityof radially extending ceramic vane structures disposed between saidradially inner and said radially outer shroud rings, each of said vanesbeing secured at one end to said radially inner shroud ring by an innersupport structure, each of said vanes being secured at its other end tosaid radially outer shroud ring by an outer support structure,

said inner support structure comprising an inner ceramic end cap,

said outer support structure comprising an outer ceramic end cap,

lationship therebetween,

1. An inlet nozzle for a gas turbine comprising: a radially inner shroudring, a radially outer shroud ring coaxial with said radially innershroud ring, a plurality of radially extending ceramic vane structuresdisposed between said radially inner and said radially outer shroudrings, each of said vanes being secured at one end to said radiallyinner shroud ring by an inner support structure, each of said vanesbeing secured at its other end to said radially outer shroud ring by anouter support structure, said inner support structure compRising aceramic end cap, an insulator pad and an inner shoe plate disposed onsaid inner shroud ring, said outer support structure comprising aceramic end cap, an insulator pad, an outer shoe plate and a biasproducing means, said outer shoe plate being movable connected to saidbias producing means, said bias producing means reacting cooperativelywith said outer ring, wherein said bias producing means provides acompressive force directed radially inwardly on each of said ceramicstructures, said bias producing means consists of a rod-like plungercooperatively associated with a spring member to induce a compressiveforce upon said ceramic structure, said plunger having a hemisphericalsurface on its inner end to provide a movable interface with respect tosaid outer shoe which has a mating hemispherical surface.
 2. An inletnozzle for a gas turbine comprising: a radially inner shroud ring, aradially outer shroud ring coaxial with said radially inner shroud ring,a plurality of radially extending ceramic vane structures disposedbetween said radially inner and said radially outer shroud rings, eachof said vanes being secured at one end to said radially inner shroudring by an inner support structure, each of said vanes being secured atits other end to said radially outer shroud ring by an outer supportstructure, said inner structure comprising a ceramic end cap, aninsulator pad and an insulator plate disposed on said inner shroud ring,said outer support structure comprising a ceramic end cap, an insulatorpad, an outer shoe plate and a bias producing means, said outer shoeplate being movably connected to said bias producing means, said biasproducing means reacting cooperatively with said outer ring, whereinsaid bias producing means provides a compressive force directed radiallyinwardly on each of said ceramic structures, said end caps havingrounded grooves, said end caps having increasing thickness in thedownstream direction, said vanes having their inner and outer endsrounded to mate with said rounded grooves in said end caps, to provideadditional compressive forces on said ceramic structures due to thefluid load upon said vanes in the direction of elastic fluid flow.
 3. Aninlet nozzle for a gas turbine comprising: a radially inner shroud ring,a radially outer shroud ring, a plurality of radially extending ceramicvane structures disposed between said radially inner and said radiallyouter shroud rings, each of said vanes being secured at one end to saidradially inner shroud ring by an inner support structure, each of saidvanes being secured at its other end to said radially outer shroud ringby an outer support structure, said inner support structure comprisingan inner ceramic end cap, said outer support structure comprising anouter ceramic end cap, said vanes being tapered to decreasing downstreamlengthwise dimensions, said vanes having generally rounded ends, saidend caps being tapered to increasing downstream radial dimensions,wherein said taper of said end caps matches the taper of said vanes,said end caps having rounded generally axially directed grooves, saidrounded ends of said vanes mating with said rounded grooves in said endcaps to provide a slight pivotable yet generally compressible supportingrelationship therebetween.